Collapsible stocks for firearms historically have a noticeable amount of tolerance, rattle, or relative movement between the stock and a receiving member, such as a receiver extension or adapter, of the firearm. This has typically been accepted by manufacturers in the industry providing after-market stocks intended for use with a variety of firearms, because the manufacturers provide stocks that accommodate the differences in standards that, even where purportedly working from the same pattern, do not necessarily adhere to the tolerance standards of the particular pattern. For example, even within a single pattern from a single manufacturing entity, movement of the stock relative to the receiving member of the firearm may reach an unacceptable level at the extremes of the manufacturing tolerances for the firearm, including the receiving member of the firearm (e.g. receiver extension or adapter) and the stock.
An undesirable amount of movement or rattle can adversely affect stability and accuracy of the firearm to which the stock is mounted, and, importantly, affect the perception of quality of the stock and firearm even if the accuracy is not affected. Over time, the relative movement can lead to damage to the stock and/or the firearm in some cases. Some in the industry have developed a variety of stabilizing mechanisms; however, currently-available designs are quite expensive and/or not suited for the retail consumer.
For example, U.S. Pat. No. 8,555,541, issued on Oct. 15, 2013 to Ingram (hereinafter “the '541 patent”) discloses a removable butt stock with two anti-rattle springs mounted within the receiver bore that press against the buffer tube to securely hold it in place within the receiver bore and prevent any potential rattle or shimmy (see FIG. 7 of the '541 patent). While functional, the invention disclosed in the '541 patent requires the use of springs that double the cost of manufacturing the stock. In some cases, the springs may damage the buffer tube or receiving member.
U.S. Pat. No. 8,191,299, issued on Jun. 5, 2012 to Faifer (hereinafter “the '299 patent”), also attempting to mitigate relative movement between the stock and the receiver extension, discloses a stock with a buffer tube holder having one or two buffer tube support members. The support members are flaps defined by a U-shaped slot. While functional as an anti-rattle feature, the flaps pose at least two problems. First, the flaps are always in an engaged position, so that, when the user assembles, disassembles, and/or adjusts the stock, the flaps cause friction on the stock, potentially resulting in unsmooth movement between the stock and the buffer tube. Moreover, after the stock is left installed on the buffer tube for an extended period of time, as can be expected under normal use, the flaps disclosed in the '299 patent are subject to creep, resulting in a loosening of the flaps from engagement with the buffer tube and a degradation or loss of the anti-rattle feature.
There therefore remains a need in the industry for a collapsible stock that provides an anti-rattle feature using fewer parts than those currently-available in the industry, while also being suited for use with a variety of manufacturing tolerance standards, and that will retain functionality and tight fitment over extended periods of time.